1. Field of the Invention
The present invention relates to a method for reducing power consumption in a communication apparatus that belongs to a plurality of networks.
2. Description of the Related Art
Recently, a wireless local area network (hereinafter, wireless LAN) system compliant with Institute of Electrical and Electronics Engineers (IEEE) 802.11 has come into wide use. Network modes of the wireless LAN includes an infrastructure mode where stations (terminal stations) communicate with each other via an access point (base station), and an ad hoc mode where the stations directly communicate with each other.
Recently, a communication apparatus has been put into the market, which has both of an access point function for performing communication as an access point and a station function for performing communication as the station by being connected to the access point. Such a communication apparatus can form a wireless network by becoming an access point itself according to the situation. The communication apparatus can also participate, as a station, in a wireless network formed by another access point.
U.S. Patent Application Publication No. 2007/0297347 (Japanese Patent Application Laid-Open No. 2008-005316) discusses an example of performing wireless communication with another communication apparatus by using one of the access point function and the station function. U.S. Pat. No. 7,362,722 (Japanese Patent Application Laid-Open No. 2005-086350) discusses an apparatus that participates in a first wireless network formed by an access point as a station, and forms a second wireless communication as an access point itself to perform communication.
In the wireless LAN, to reduce power consumption, the station can operate in a power-saving mode for stopping power supplying to a wireless communication unit for a predetermined period. On the other hand, the access point cannot operate in the power-saving mode because the access point has to perform participation or breakaway of stations in or from the wireless network formed by itself and relay communication between the stations.
However, power consumed by the communication apparatus that simultaneously operates both station and access point functions, as discussed in U.S. Pat. No. 7,362,722, is expected to be large. Especially, when the communication apparatus is a batter-activated device, it is desirable to reduce power consumption more.
However, the shift of such a communication apparatus to the power-saving mode as in the case of a usual wireless LAN station may disable data communication between apparatuses in the second wireless network formed by the communication apparatus itself.